Question

[le tien thanh]

(1/2+1/12+1/20+1/30+.....+1/3540)*x=147/20

Answer 1

[Nguyễn Anh Quân]

=> (1/2+1/3.4+1/4.5+.....+1/59.60).x = 147/20

=> (1/2+1/3-1/4+1/4-1/5+.....+1/59-1/60).x = 147/20

=> (1/2+1/3-1/60).x = 147/20

=> 49/60.x = 147/20

=> x = 147/20 : 49/60 = 9

Vậy x = 9

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